class ListNode{
    public int val;
    public ListNode next;
    public ListNode(int val){
        this.val=val;
    }
}
public class MyLinkedList {
    public ListNode head;

    public void createList(){
        ListNode listNode1=new ListNode(12);
        ListNode listNode2=new ListNode(23);
        ListNode listNode3=new ListNode(34);
        ListNode listNode4=new ListNode(45);
        ListNode listNode5=new ListNode(56);
        listNode1.next=listNode2;
        listNode2.next=listNode3;
        listNode3.next=listNode4;
        listNode4.next=listNode5;
        this.head=listNode1;
    }

    public void display(){
        ListNode cur=head;
        while(cur!=null){
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
        System.out.println();
    }

    //查找单链表中是否包含关键字key
    public boolean contains(int key){
        ListNode cur=head;
        while(cur!=null){
            if(cur.val==key){
                return true;
            }
            cur=cur.next;
        }
        return false;
    }

    //求单链表的长度
    public int size(){
        int count=0;
        ListNode cur=head;
        while(cur!=null){
            count++;
            cur=cur.next;
        }
        return count;
    }

    //头插法
    public void addFirst(int data){
        ListNode node=new ListNode(data);
        if(head==null){
            head=node;
        }else{
            node.next=head;
            head=node;
        }
    }

    //尾插法
    public void addLast(int data){
        ListNode node=new ListNode(data);
        if(head==null){
            head=node;
        }else{
            ListNode cur=head;
            while(cur.next!=null){
                cur=cur.next;
            }
            cur.next=node;
        }
    }


    //找到index-1位置的节点地址
    public ListNode findIndex(int index){
        ListNode cur=head;
        while(index-1!=0){
            cur=cur.next;
            index--;
        }
        return cur;
    }
    //任意位置插入
    public void addIndex(int index,int data){
        if(index<0||index>size()){
            System.out.println("index位置不合法");
            return;
        }
        if(index==0){
            addFirst(data);
            return;
        }
        if(index==size()){
            addLast(data);
            return;
        }
        ListNode cur=findIndex(index);
        ListNode node=new ListNode(data);
        node.next=cur.next;
        cur.next=node;
    }


    //删除第一次出现关键字为key的节点
    public void remove(int key){

    }




    public static void main(String[] args) {
        MyLinkedList myLinkedList=new MyLinkedList();
        //myLinkedList.createList();
        myLinkedList.addFirst(23);
        myLinkedList.addFirst(34);
        myLinkedList.addFirst(45);
        myLinkedList.addFirst(56);
        myLinkedList.addLast(3);
        myLinkedList.addIndex(0,99);
        myLinkedList.addIndex(6,88);
        myLinkedList.addIndex(9,77);
        myLinkedList.display();
        System.out.println(myLinkedList.contains(56));
        System.out.println(myLinkedList.size());;
    }

}
